This research is an investigation of synaptic interactions in the retina of the eye. More specifically, this research will concentrate on synaptic processing in the outer plexiform layer with an emphasis on identifying the synaptic transmitter substance released by photoreceptors and determining the actions of this transmitter. This study will use a newly developed technique called noise analysis. This analysis will allow characterization of how the postsynaptic channels in bipolar cells are affected by the photoreceptor transmitter. Putative transmitters will be superfused onto the retina and the noise analysis technique will again be used to characterize properties in bipolar cells. Comparing the properties of the channels under the normal and perfused states will allow us to identify the natural transmitter. A second part of this study will involve the fabrication of substrate specific electrodes which will be employed to measure directly the release of neurotransmitter from retinal neurons. This technique involves the use of pH or NH+ detectors coated with a gelatin which is embedded with an enzyme that degrades or hydrolyzes the neurotransmitter producing NH+ or H+ ions.